Hard reset TP-LINK TD-W8970

Factory reset (Hard reset) Power ON the modem router. Find the reset button hole on the rear panel, press in it with a pin or paperclip and hold like that for 8 to 10 seconds before releasing. Wait a minute or two for the device to go back to its factory defaults.
Firmware Firmware link
Default username admin
Default password admin
Default IP address 192.168.1.1